A marked improvement of efficiency in infection of tobacco mesophyll protoplasts with plant viruses and virus RNAs by using polyethyleneimine as a polycation.

Abstract

In attempts to search polycations suitable for inoculation of tobacco mesophyll protoplasts with virus RNA, polyethyleneimine (PEI) was found to be the most competent on which markedly improved the efficiency of infection not only with cucumber mosaic virus (CMV) RNA and tobacco mosaic virus (TMV) RNA but also with CMV and tobacco necrotic dwarf virus (TNDV). For inoculation with virus RNAs and viruses, 25mM phosphate buffer, pH 5.0, and 10mM citrate buffer, pH 5.5, respectively, were found to be suitable. Over 90% of protoplasts could be constantly infected using CMV RNA and TMV RNA concentrations as low as 0.2 to 0.3μg/ml. The ratio of RNA and PEI was very important and excess amounts of RNA in inoculation mixtures lead to the drastic decrease in infection efficiency.